Twelve-year-olds Ella Yellich-O'Connor, David Sorrenson, Thomas Calver and 11-year-old Ella Brownlie, will fly to Johannesburg on July 31.
Two of the team took part in last year's final of the quiz, which they just missed out on winning.
"We came second last year which was very disappointing but it's very good that we've won this time," said Thomas.
"I'm just glad that we actually have a chance to compete in the final," said Ella Yellich-O'Connor, who also took part in last year's contest.
The students said they were excited by the prospect of visiting South Africa and seeing the big game parks and Nelson Mandela's home.
"I haven't been out of New Zealand so I'm really looking forward to it. We get to go to a safari park so that should be pretty mean," said Ella Yellich-O'Connor.
The quiz aims to motivate children to read by challenging their knowledge of literature in a competitive environment.
Competitors must read young adult literature widely - there is no set reading list - and then answer book-related questions in the contest.
The New Zealand final of the competition took place on Sunday, with 14 teams from around the country taking part.
The prize for winning the national final was $12,000, which would go towards travel costs for the trip, plus a whole lot of books.
The students will face five other teams from around the world in the final, and they are reading up to 30 books each a week in preparation for the contest.
Team coach Jenny Armitage said the team was chosen carefully.
"I give a lot of tests in the beginning to determine which children I will train," she said.
The quiz is the brainchild of Wayne Mills, a senior lecturer at the University of Auckland education faculty.
He started the quiz in 1991 because he believed children weren't being rewarded for reading in the way they were rewarded for sports and mathematics. The final is in Pretoria, on August 3.